The use of prescription antiviral drugs, as well as the voluntary use of infection-preventing products which are readily and economically available are of importance when suppressing virus-induced infectious diseases which can spread infection on a large-scale among the humans and animals, making them critically ill and attacking the economy (Annu. Rev. Pharmacol. Toxicol. 49, 349-375 (2009)).
Such individual and voluntary preventive measures will become effective, especially against infection of influenza virus, herpes virus, HIV and the like because those viruses can be inactivated relatively easily although they are highly infectious. Based on the above-mentioned concept, several clinical surveys were conducted among the subjects at high risk of HIV infection in the African countries in order to verify the prevention of HIV infection by using sterilizers which contain a surfactant as the main ingredient and are available without any medical prescription at reasonable prices. Although HIV was inactivated temporarily, those studies ended in tragedy because the mucosal tissues of the subjects became inflamed, which unfortunately accelerated the HIV infection (BMC Infectious Disease 6: 90 (2006); Lancet Infectious Disease 8, 685-697 (2008); and Journal of Antimicrobial Chemotherapy 55, 420-423 (2005)).
In general, surfactants can effectively inactivate the viruses, while the tending to induce an immune response of the living organism by the tissue damaging property. The use of surfactants is therefore extremely limited in the diseases where viruses are increasing on the mucosal tissue.
It has been also hitherto believed in the Western countries that very familiar acidic foods such as table vinegar, lemon juice, lime juice and the like can be used to inactivate viruses and prevent infectious diseases. Recently, clinical tests were conducted to verify the effects and safety of this hypothesis. According to the reports, these acidic foods have little effect on the prevention of infectious diseases. On the contrary, it has been found that side effects are conspicuously induced, for example, introduction of new infectious diseases, occurrence of acute disorders, and the like (Journal of Woman's Health 16, 1041-1051 (2007); and Sexual Health 33, 73-79 (2004)). Another treatment is local administration of lactobacilli, which has been hitherto believed to be a safe and specific remedy. This treatment aims to enhance the effect of protecting the mucosal tissue by using a peptide factor produced by lactobacilli and the obtained acidic pH. However, the above-mentioned treatment has been found to involve unexpected risks, such as development of infectious diseases caused by the pathogenic microbes mixed in the lactobacilli, activation of the tissue-derived factors to accelerate the growth of HIV by the action of lactobacilli, and the like (Sexual Health 33, 73-79 (2004)). In the clinical studies aiming to prevent HIV infection, to protect the mucosal tissue from virus- and microbe-infection using an acidic pH environment as the tissue takes advantage of lactobacilli flora, some attempts are now in progress to ensure a stronger and stabler acidic environment by local administration of a gel containing an acidic buffer (Clinical Infectious Diseases 32, 476-482 (2001)).
Those tests aim at finding a so-called mucosal environment protection enhancer. As yet no conclusion has been reached in regard to whether the acidic buffer-containing gel itself works to inactivate the viruses based on the generated acidic pH environment. It has been reported that the acidic pH does not in fact function and is a physical barrier of the gel that effectively works (Sexually Transmitted Diseases 29, 655-664 (2002)).
In Chinese medicine, many examples have been reported of natural products derived from particular plants and animals that can highly inactivate viruses or highly suppress the growth of viruses in the virus-infected cell or tissue. There is much research being conducted to look for natural products capable of inactivating viruses (Virologica Sinica 23, 305-314 (2008)).
However, it is not easy to find an ingredient that can produce the virus-inactivating effect and is safe for the living body, even if the ingredient is derived from natural products. In most cases, the acting mechanism of those active natural products has not yet been ascertained, which inhibit the development of those ingredients derived from natural products as therapeutics for infectious diseases or infection inhibitors (Virologica Sinica 23, 305-314 (2008)).
Arginine, one of the amino acids found in the living body, is a remarkably safe ingredient and also is known to exhibit an effective virus-inactivating effect by appropriately adjusting its concentration and pH (Japanese Patent Unexamined Publication (“JP Kokai”) No. 2009-263231; Journal of Pharmaceutical Sciences, 97, 3067-3073 (2008); and International Journal of Pharmaceutics 361, 92-98 (2008)).